Fast-paced action and suspenseful!  Not  really sure what was the reason why people are going berserk  but one thing that draws your attention to this film is the  action and suspense!  I presume these are not zombies as they move fast but it seems that their minds are possessed by something else.  The passenger of the man bit him,  but judging that the taxi driver didn't change into a  monster means that the malady may be something else.  This is worth checking out especially for those who love horror and action genres.